The Norwegian Mother & Child Cohort Study (MoBa) is an ongoing long-term prospective cohort study of 107,000 pregnant Norwegian women and their children. In collaboration with the Norwegian National Public Health Institute (NIPH), NIEHS supported the collection of additional biologic specimens from the women when they were pregnant (blood and urine). These specimens will be used for the measurement of environmental exposures. A variety of exposure and health variables on babies, mothers and fathers are collected. Records from the cohort study will also be linked to routine national health registries. The Norwegian Mother & Child Cohort Study provides a valuable opportunity to assess the role of environmental exposures in the health of women and their children.